Vaxcyte (PCVX) Announces Publication of Preclinical Data Supporting the Potential of VAX-24 for the Prevention of Invasive Pneumococcal Disease

Vaxcyte, Inc. (Nasdaq: PCVX), a next-generation vaccine company seeking to improve global health by developing superior and novel vaccines designed to prevent or treat some of the most common and deadly infectious diseases worldwide, today announced the publication of preclinical data supporting the potential of VAX-24, its lead vaccine candidate, in the journal Vaccine. VAX-24 is an investigational 24-valent pneumococcal conjugate vaccine (PCV) designed to prevent invasive pneumococcal disease, which can be most serious for infants, young children, older adults and those with immune deficiencies or certain chronic health conditions.

Today, despite widespread PCV vaccination in infants and older adults, there continues to be considerable impact from disease-causing pneumococcal serotypes, or strains, not covered by the currently available 13-valent PCV. This is largely due to the inherent genetic diversity of Streptococcus pneumoniae, and is further exacerbated by the phenomenon of serotype replacement. High rates of morbidity and mortality due to pneumococcal disease underscore the need for a more broad-spectrum vaccine.

The paper, “Non-clinical Immunological Comparison of a Next-Generation 24-Valent Pneumococcal Conjugate Vaccine (VAX-24) Using Site-Specific Carrier Protein Conjugation to the Current Standard of Care (PCV13 and PPV23),” which includes previously disclosed data, uses a rabbit model to evaluate the immune response of Vaxcyte’s 24-valent PCV candidate compared to Prevnar13® (PCV13) and Pneumovax®23 (PPV23). In this study, all serotype conjugates in VAX-24 met the primary objective to elicit immune responses that were more robust compared to PPV23 and at least comparable to PCV13.

“Despite widespread, global use of pneumococcal conjugate vaccines, the prevalence of invasive pneumococcal disease remains high, and there is a significant unmet need for a vaccine that provides safe, effective and broader protection,” said Jim Wassil, Chief Operating Officer, Vaxcyte. “These preclinical data add to the growing body of evidence supporting the potential for VAX-24, using Vaxcyte’s proprietary cell-free protein synthesis platform, to become the broadest-spectrum PCV. We continue to advance VAX-24 in preparation for the anticipated submission of the Investigational New Drug Application to the U.S. Food and Drug Administration in order to generate clinical proof of concept in a Phase 1/2 study.”

Highlights of Study Design and Findings:

• In this study, VAX-24, PCV13 and PPV23 were administered to New Zealand White rabbits to compare the resulting opsonophagocytic, or neutralizing antibody, activity (OPA) and anti-capsular IgG antibodies generated that specifically bind to all the individual serotypes included in each respective vaccine.
• The rabbits were dosed at either 0.11µg or 1.1µg of VAX-24 at the start of the study and a booster was given 21 days later. Immunogenicity was measured 14 days after both the initial and booster doses and compared to the 13 serotypes contained in PCV13 and the incremental 11 serotypes contained in PPV23.
• In the study, VAX-24 showed conjugate-like immune responses to all 24 serotypes based on comparable OPA and IgG responses to PCV13 and higher responses than PPV23.
• This study demonstrated the utility of Vaxcyte’s site-specific conjugation technology in a preclinical setting and the potential for a PCV with broader serotype coverage.

Vaccine Paper Details and Access“Non-clinical Immunological Comparison of a Next-Generation 24-Valent Pneumococcal Conjugate Vaccine (VAX-24) Using Site-Specific Carrier Protein Conjugation to the Current Standard of Care (PCV13 and PPV23),” by Jeff Fairman, Paresh Agarwal, Sandrine Barbanel, Christopher Behrens, Aym Berges, John Burky, Peter Davey, Phil Fernsten, Chris Grainger, Sherry Guo, Sam Iki, Mark Iverson, Martin Kane, Neeraj Kapoor, Olivier Marcq, Thi-Sau Migone, Paul Sauer, and James Wassil. DOI: 10.1016/j.vaccine.2021.03.070. The paper is in press in Vaccine, Vol. 39, issue 23 (2021) published by Elsevier. The paper is available online: https://www.sciencedirect.com/science/article/pii/S0264410X21003741.

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